Breath / Blood Alcohol Concentration (BAC) Calculator

Blood/Breath Alcohol Concentration (BAC) is the amount ofalcohol in the bloodstream or on one's breath. BAC is expressed asthe weight of ethanol, measured in grams, in 100 milliliters ofblood, or 210 liters of breath. BAC can be measured by breath, blood, or urine tests.

Some states define legal intoxication for purposes of driving as having a BAC of 0.08 or greater, in most cases (please check your state for the specific BAC level of intoxication). But alcohol may affect driving skills at BACs of 0.05 or even lower.

Driving skills, especially judgment, are impaired in most people long before they show signs of drunkenness. The public usually associates BAC with "drunk driving." But it's more accurate to refer to "alcohol-impaired" driving because you do not have to be "drunk" to be impaired in your ability to safely drive a car.

How fast you drink. In general, the quicker you drink, the higher your peak BAC will be.

Body size. Large people tend to reach lower BACs than smaller people, given the same amount of alcohol.

Food in your stomach. When there is food in your stomach, alcohol is absorbed more slowly into the blood stream. The BAC rises more rapidly when you drink on an empty stomach, because there is no food in which to dilute the alcohol.

Type of mixer used. Water and fruit juices mixed with alcohol may slow the absorption process, while carbonated beverages may speed it up.

Gender differences.

Women reach higher BACs faster because they have less water in their bodies and more adipose tissue (fat), which is not easily penetrated by alcohol.

A man and a woman, with all other factors being equal, both drinking the same amount of alcohol, will have different BAC levels. Hers will be higher.